Tasmanian cave spider: 1982

Visitors to Tasmania's famous Mole Creek caves beware - wandering off the trail may leave you entangled in the giant sheet-web of Tasmania's legendary cave spider, Hickmania troglodytes.

With the leg span of an adult approaching 18 cm, coming face-to-face with one in the gloom of a cave entrance can be an unnerving experience. Yet bites are rare, as Hickmania prefers to save its energy for feasting on the occasional cave cricket or other arthropod that blunders into its metre-wide web.

Besides cave entrances, the cave spider can also be encountered across Tasmania in hollow logs, in the gaps between boulders and in the darkest recesses of bridges and cellars.

These spiders are tough, and probably live for decades. Females spin a peculiarly strong, internally partitioned egg sac that protects their eggs from fungal attack in the damp cave environment.

Hickmania is a taxonomic oddity: the sole Australian representative of an ancient spider lineage, whose nearest relatives now reside in the cool forest undergrowth of the Andes.

Some 125 million years ago, Hickmania's ancestors must have hitched a ride on those fragments of the disintegrating supercontinent of Gondwana that were to become Australia and Antarctica, leaving their cousins to their fate in what was to become South America.

As the Australian fragment then drifted north into warmer climes, the spiders were only able to survive in the continent's southernmost outpost, Tasmania; meanwhile, the Antarctic fragment became just too cold.

The cave spider was originally described as new to science in 1883, based on a specimen from a cave at Chudleigh, near Mole Creek.

In 1958, when its uniqueness was more fully appreciated, it was given the generic name Hickmania, in honour of University of Tasmania Professor of Biology, Vernon Hickman. Hickman had a particular interest in Tasmanian spiders, describing many new species and authoring a landmark book on the subject in 1967.